Now that golden beets and purple potatoes are practically supermarket staples, some California citrus growers are betting that cooks are ready for the next new thing.

Navel oranges still account for most of the state's citrus business, but in recent years a few specialty growers have been harvesting such rarities as sour oranges, Buddha's Hand citron, Cara Cara oranges, limequats, Lavender Gems and bergamot.

With a winter citrus palette that also includes Oroblanco and Melogold hybrid pomelos, blood oranges, Meyer lemons, Mexican and Rangpur limes and mandarin oranges, chefs and shoppers are enjoying a citrus revolution.

"I love having this citrus 'wardrobe,' " says Niloufer Ichaporia, an Indian- born culinary anthropologist in San Francisco. "I don't use them in a conscious way. I just grab and squeeze and try to have as many kinds as possible on hand at any one time."

Although many consumers are reluctant to move beyond the familiar winter navel oranges, grapefruit and Satsuma mandarins, curious cooks can now play around with a remarkable citrus parade.

Some are bone-jarringly tart (the limequat, the calamondin), some famously aromatic (the citron, the bergamot), some deliciously tart-sweet (the Page mandarin, the cocktail grapefruit). And, as usual, chefs are leading the way.

"I don't understand why people are afraid of these beautiful citrus," says Amaryll Schwertner, chef at Stars in San Francisco. "Americans don't use nearly as much citrus in cooking as they could."

COMPLEMENTING COUSCOUS

At Stars, Schwertner preserves limequats Moroccan-style in salt and spices, then uses them as a condiment for couscous. Tangerine zest perfumes her lamb and chestnut stew, yuzu (a lemon-like Japanese citrus) goes in tartar sauce and marinades.

She rolls Meyer lemons in salt to make a "lemon salt" seasoning and, at home, makes what she calls "the best vodka drink there ever was" with vodka and the juice of Oroblancos, a grapefruit-pomelo cross that tastes like a supersweet, low-acid grapefruit.

In Stars' pastry department, chef Sara Spearin uses a wide range of citrus in sorbets and compotes for diners who don't have much of a sweet tooth. She serves blood orange sorbet in candied slices of Buddha's Hand, the beguilingly perfumed fruit that resembles a weirdly distorted hand. The scalloped slices are stunning to look at, with a haunting taste somewhere between lemon and camphor. (In fact, citron peel, like camphor, is used in some moth repellents.)

"I think there are real reasons why we crave citrus at this time of year," says Jennifer Cox, chef at Montage in San Francisco. Cox uses Cara Cara oranges, blood oranges, Meyer lemons and kumquats in salads and desserts, in part to balance the robust braised dishes that diners also seek out in winter.

"People need something to brighten up their palates because everything else is so low-toned," Cox says. "Citrus makes you feel like you're getting a little sunshine and vitamin C."

A QUEST FOR DIVERSITY

One reason a greater variety of citrus is available today is that growers like Lance Walheim have branched out. Walheim, a horticulture writer for Sunset magazine, was researching a book on citrus years ago and visited the University of California's Lindcove Field Station near Fresno. This agricultural research facility maintains the "mother block" of virus-free, true-to-type citrus, the source of propagation material for the California citrus industry.

"I saw there were a lot of varieties that people weren't getting to eat," Walheim says. He began experimenting with the Lindcove fruit, taking some of it to the Oakville Grocery in Napa Valley to test consumer interest. Then he talked a few growers into planting some blood oranges and Oroblancos. When those sold well, he and partners Mike and Barbara Foskett bought their own groves south of Fresno.

Fifteen years later, the partners are growing some 30 different unusual citrus varieties on about 25 acres. Their company, California Citrus Specialties, also represents other growers and sells to brokers all over the world.

Specialty citrus offers a profitable niche for small-production growers like Walheim, who can't compete in the commodity world of navels and Valencias.

Last year he picked 160,000 pounds of navels from trees he inherited when he bought his property. It made him $700. Not surprisingly, he can do much better selling Meyer lemons to Napa Valley's Domaine Charbay for its flavored vodka, or to O, the flavored olive oil producer. Some of his specialty produce goes to Monterey Foods in Berkeley or to the San Francisco produce market, both conduits to the Bay Area's restaurant chefs.

Ironically, once growers like Walheim create a profitable market for a specialty crop, the larger growers want a piece of the business. Oroblancos are a cautionary example. Eager to get a high price by being the first in the market each season, growers were picking their Oroblancos underripe, Walheim says. Consumers were turned off by the green-tasting fruit, and the demand for Oro-blancos dropped. The Japanese, who were avid customers, refused to take any more California Oro-blancos. Acres of the fruit were ripped out.

QUALITY IS CRUCIAL

If there's a silver lining, it's that the remaining growers are more quality-conscious, Walheim points out. They're bringing their fruit to market later, when the sugar-acid ratio is higher and the flavor better. But Walheim seems acutely aware that consumer trust is fragile, and that growers can easily ruin a market when they sacrifice taste for short-term profit.

Tasting Walheim's mandarin oranges straight from his trees reinforces the shortcomings of much supermarket citrus. His Pixie mandarins have a thickish, bumpy rind that's not particularly attractive in the marketplace, but underneath lies sweet, juicy, seedless fruit with a sharp burst of acid. The Page mandarins are even sweeter and more succulent.

"Once you try one, you never forget it," the grower says. "You can smell it a mile away when you cut it, and it has a richness and character that I think of as mandarin flavor."

Mandarin oranges are a primary focus of California citrus research, says Louis Whitendale, superintendent of the Lindcove station. Because profits are sagging in the navel orange industry, growers are looking for new varieties such as Clementine mandarins. They want easy-to-peel Clementines that size up nicely. They want early-, mid- and late-season varieties to extend their harvest season. And they want their Clementines seedless -- a hybridizing challenge, Whitendale says.

ABUNDANT CHOICES

As a stroll through the fenced mother block at Lindcove shows, growers have no shortage of citrus choices. They can order budwood from 30 different mandarins, five different blood oranges, dozens of pomelos, grapefruits, tangelos and tangors. The mother block has sour oranges, Mexican limes, variegated pink lemons (no, they don't make pink lemonade), Kaffir lime, bergamot, calamondin, mandarinquats, and three kinds of citron. "There's a huge selection available," Whitendale says. "The question is, 'Is there enough market?' "

One of the market-makers in specialty citrus is Bill Fujimoto of Berkeley's Monterey Foods. His many chef-customers look to him to hear what's new and good.

Cara Cara is an eye-catching pink-fleshed navel, a mutation that occurred naturally on a navel tree in Venezuela. Chefs have embraced it as readily as they flocked to golden beets, pairing it with blood oranges and ruby grapefruits in sorbet trios and winter salads.

Fujimoto also expects to see more fresh California Kaffir limes in the market because the leaves and peel are essential to Thai cooking. "Everybody says they've planted a tree," he says, but currently the steadiest supply comes from Florida.

In contrast, Meyer lemons have been so widely planted that the market may struggle to absorb them. But not for long, Fujimoto predicts. "All you have to do is ship them to Kansas City and demo them and the market will take over. I would think any fish restaurant would love to have Meyer lemons."

Fujimoto is also looking forward to the University of California's new mandarin hybrids, which will show up over the next few years as newly planted trees begin bearing. In the meantime, he's shaking his head over the underwhelming reception for the Oroblanco, another university creation that achieved the hybridizers' holy grail: a sweet grapefruit.

"We've been selling them since the 1980s. They're wonderful, but consumers don't know what's inside. Navels and grapefruits are cheap, so it's hard to get people to jump in," he says. Those who do will find a deeply flavorful breakfast fruit that's more tart than an orange but sweeter than a conventional grapefruit, with few or no seeds.

PASTRY CHEF'S PASSION

Lindsey Shere, former Chez Panisse pastry chef, was an early convert to Lavender Gems, Oroblancos, Clementines, Meyer lemons and other unusual citrus - - most of which she discovered through Fujimoto. Her 1985 cookbook, "Chez Panisse Desserts," includes recipes for Lavender Gem sherbet, blood orange ice cream and Meyer lemon souffle. She is still an enthusiast and a student. At the recent Slow Food conference in Italy, she found a Sicilian bergamot marmalade that she is attempting to recreate with bergamot grown at her Healdsburg home. Kumquats are another favorite.

"I love to eat them just straight," she says. "They have that sweet skin and sour flesh. At the restaurant, we did a lot of candied kumquats for candy plates. And they're so beautiful sliced and poached with other fruits in citrus compotes. I love kumquats. I have a little tree finally, and it makes me happy."

For citrus fans and cooks who welcome citrus in the kitchen, it's indeed time to rejoice.

-- BLOOD ORANGE. A sweet orange with flesh that may be deeply red or merely blushed with red. Some varieties have blushed rinds, others don't. The Moro tends to have considerably more internal color than the Sanguinelli or Tarocco, the two other common varieties. A properly ripened blood orange can have an almost raspberry-like flavor. Great for juicing.

-- CALAMONDIN. An acidic fruit that resembles a large kumquat, the Calamondin is popular among Filipino and Hawaiian cooks. Its parents are unknown. Calamondin trees bear fruit profusely and are highly ornamental.

-- CARA CARA ORANGE. An atypical "sport" that appeared on a Venezuelan navel tree, the sweet pink-fleshed Cara Cara navel is growing rapidly in popularity. It looks like an orange on the outside, like a ruby grapefruit on the inside.

-- ETROG CITRON. Resembling large, bumpy lemons, citrons are believed to be from India and were the first citrus to reach Europe. Citron is a ceremonial and medicinal fruit in Indian culture and, known as etrog, a ceremonial presence at the Jewish harvest festival of Sukkot.

-- BUDDHA'S HAND CITRON. The fingered Buddha's Hand is doubtless one of the strangest-looking fruits on earth. Along with etrog citron, it is valued for its aromatic rind and has virtually no pulp or juice.

-- COCKTAIL GRAPEFRUIT. A pomelo/mandarin cross, the cocktail grapefruit ranges in size from a small grapefruit to a small pomelo. It resembles a grapefruit on the outside; inside, its flesh is pale orange, seedy and sweet, with a vaguely tropical taste.

-- KAFFIR LIME. The Kaffir, also spelled Kieffer, lime is valued in Southeast Asian cooking for its leaves and fragrant zest, both of which have a camphorlike scent. The fruit looks like a bumpy lime. The juice is sour and there's not much of it.

-- KEY LIME. Also known as Mexican lime, the Key lime is smaller, seedier, juicier and more fragrant than the common Persian, or Tahitian, lime.

-- KUMQUAT. The kumquat has sweet orange skin and seedy, tart-sweet flesh. Unlike other citrus varieties, the fruit is eaten whole, skin and all. Some varieties are as small as a pea but the more common ones are about the size of a large olive. The most common varieties in California are the round Meiwa and the elongated Nagami.

-- Lavender Gem. Also known as Wekiwa, the Lavender Gem is a grapefruit- tangelo cross. It resembles a small grapefruit, but the tangy, pink-blushed flesh is sweeter.

-- LIMEQUAT. Resembling a very small, round lemon (some varieties are oblong), the limequat is a lime-kumquat cross. It is limelike in flavor but less frost-tender than a lime, thanks to its kumquat parentage.

-- MANDARIN ORANGES. The large and growing mandarin family includes the Page, Dancy, Honey, Satsuma, Fairchild and Clementine varieties. Mandarins generally have thin, easy-to-peel skin and separate easily into segments. They may be seedless or seedy. A ripe mandarin is fragrant, juicy and sweet with a hint of acidity. They are great choices for breakfast juice.

-- MANDARINQUAT. A mandarin-kumquat cross with tart juice.

-- MELOGOLD. Developed by the University of California, the Melogold is grapefruit-pomelo cross. Its rind is thicker than a grapefruit's but thinner than the Oroblanco's. It produces large, meaty, sweet and juicy segments with less tang than a grapefruit.

-- MEXICAN LIME. Same as Key lime.

-- MEYER LEMON. Thought to have a lemon and either a mandarin or an orange as parents, the Meyer has a thin yellow-gold or yellow-orange rind and yellow flesh tinged with orange. It is sweeter, less tart and more fragrant than the common Eureka or Lisbon lemon.

-- OROBLANCO. A University of California cross between a grapefruit and a pomelo, the Oroblanco is an exceptionally sweet, juicy and tasty fruit. Consumers tend to scorn it because it has less flesh and thicker rind than a grapefruit, but its flavor can be outstanding -- sweet, with a touch of acid and no bitterness.

-- RANGPUR LIME. Resembling a mandarin orange, the reddish-orange Rangpur lime can surprise the unsuspecting taster. Even inside, it resembles a sweet mandarin, but its orange juice is quite tart and tropical.

-- BERGAMOT. Possibly the offspring of a sour orange and sweet lime or lemon, bergamot resembles a large, rough-skinned lemon. The peel is highly aromatic and its oils are used in perfumes and Earl Grey tea.

-- SEVILLE OR SOUR ORANGE. Although referred to generically as Seville orange, domestic sour oranges may or may not be the same as the famous Spanish trees. With its fragrant, bitter peel and tart juice, this is the orange for a proper British marmalade. Sour orange juice is also called for in many Mexican and Cuban recipes.

-- TANGELO. A cross between a mandarin and grapefruit or pomelo. The Minneola is the most familiar tangelo, recognizable by its raised neck. They peel as easily as a mandarin, and have juicy, sweet-tart flesh. They may or may not have seeds.

-- TANGERINE. A commercial name usually given to deeply colored mandarins such as the Dancy. It has no botanical meaning.

-- TANGOR. Thought to be a mandarin crossed with an orange, the tangor is sweet-tart, rich in flavor and juicy, with many seeds. The Temple is probably the most widely available tangor in California. It's a good choice for juice.

GROW YOUR OWN

Four Winds Growers in Fremont provides a large range of dwarf citrus to the nursery trade, and many local nurseries carry Four Winds citrus.

Don Dillon Jr., the grandson of the founder, says that Bay Area residents can succeed with many of the more unusual citrus, especially if they are grown in containers so they can be moved to protect them from frost.

Citrus need heat to develop sweetness, so kumquats, blood oranges, mandarin oranges, Cara Cara oranges and the pomelo hybrids do best in warmer inland areas. Most of these fruits are also relatively cold-tolerant.

Frost-sensitive citrus such as limes and citron will need winter protection in inland areas.

Consult your local nursery for advice about appropriate citrus varieties for your area.

WHERE TO FIND THE CITRUS

Many well-supplied supermarkets, such as Whole Foods, Draeger's, Andronico's and Mollie Stone's, carry some of the more unusual varieties. But the following generally have a complete selection or are good sources for a particular fruit:

-- Greenleaf Produce, 1955 Jerrold Ave., (off Bayshore or off Third Street) San Francisco; (415) 647-2990. Although Greenleaf is a produce wholesaler, the company will sell to individual cash customers willing to pick up at its produce market warehouse. Call ahead to order.

WINE RECOMMENDATIONS

Here are some wine suggestions for today's citrus recipes. -- Insalata's Walnuts, Kumquats & Picholine Olives. This well balanced salad includes lots of textural contrasts. Try a California Viognier, which has fresh fruit flavors in a soft manner. The lean acidity will brighten the olive components creating a symphony of flavor and texture. Readily available is the well-made R. H. Phillips Viognier. -- Mixed Citrus Compote. Freshness is the key to this delightful dessert. Complexity is added by the kirsch and spices. The perfect companion is Quady Electra Orange Muscat California 1999 -- a light, fizzy, low-alcohol, refreshing wine. -- Mixed Citrus Salad With Avocado & Fennel. Citrus brings brightness to the lush flavors and textures of avocado. To compliment this combination and bring forward the fennel, try a dry, high-acid wine with nice fruit concentration. Trefethen Napa Valley Riesling has all these qualities and will marry with the dish to create sunshine on the palate. -- Echo's Chicken Breasts With Citron. A dish like this needs a dry, high- acid wine with clean flavors and little or no oakiness. Try Lapostelle Sauvignon Blanc from Chile. There are true Sauvignon Blanc grapefruitlike flavors without an excess of grassy character. The wine is crisp and yet full in flavor, with the body to marry the richness of the chicken. -- Stars' Candied Buddha's Hand With Blood Orange Sorbet. This simple dish has some complex flavors. A nice wine to serve is Banfi Brachetto. Brachetto is a light, fruity, off-dry, red sparkling wine from the Piedmont region of Italy. It will lift the sorbet and show off the wonderful blood orange flavors. There is enough body and texture to work nicely with the Buddha's Hand.

-Diane Teitelbaum

MIXED CITRUS SALAD WITH AVOCADO AND FENNEL

This dish is adapted from a recipe by Jennifer Cox, chef at Montage in San Francisco.

INGREDIENTS:

Dressing

1 shallot, minced

1 tablespoon lemon juice

1 tablespoon honey

Salt and freshly ground black pepper

1/4 cup extra virgin olive oil

Salad

2 Cara Cara oranges

1 blood orange

1 head red leaf lettuce

1/2 large bulb fennel, very thinly sliced crosswise

1/2 avocado, thinly sliced crosswise

INSTRUCTIONS: To make the dressing: In a bowl, whisk together shallot, lemon juice, honey, and salt and pepper to taste. Whisk in the olive oil. Taste and adjust seasonings, if necessary.

To make the salad: Cut a slice off the top and bottom of all three oranges. Set the fruits on one end so they will stand upright. With a sharp knife, remove all the peel and white pith by slicing from top to bottom all the way around the fruits, following their contour. With a small knife, remove the individual segments from the membranes and place them in a bowl.

Tear the lettuce into bite-size pieces and place in a large serving bowl. Add enough of the dressing to coat the leaves lightly. Toss the fennel with some of the dressing and scatter over the top of the salad. Scatter citrus segments over the top. Dress the avocado with remaining dressing and scatter over the top of the salad. Serve immediately.

MIXED CITRUS COMPOTE

Serve in compote dishes or balloon wine glasses with warm gingersnaps or other spice cookies.

INGREDIENTS:

1 ruby grapefruit

2 Cara Cara oranges

2 blood oranges

2/3 cup white wine

2/3 cup water

1/2 cup sugar

1 cinnamon stick

1 clove

2 whole cardamom pods

2 teaspoons kirsch, or to taste

INSTRUCTIONS: Cut a slice off the top and bottom of the grapefruit and both kinds of oranges. Set the fruits on one end so they will stand upright. With a sharp knife, remove all the peel and white pith by slicing from top to bottom all the way around the fruits, following their contour. Working over a bowl to catch any juices, remove the individual segments from the membranes with a small knife, letting them fall into the bowl. Squeeze the empty membranes into the bowl to release more juice.

In a small saucepan, combine the wine, water, sugar, cinnamon and clove. Break open the papery cardamom pods and add the seeds to the liquid; discard the pods. Bring to a simmer over high heat, lower heat and simmer until reduced to 1/2 cup. Strain syrup over fruit to remove the spices. When cool, cover and refrigerate until chilled. Just before serving, stir in the kirsch.

STARS' CANDIED BUDDHA'S HAND WITH BLOOD ORANGE SORBET

INGREDIENTS

Candied Buddha's Hand

1 Buddha's Hand citron

3 cups water + more for cooking citron

3 cups sugar

Sorbet

3 cups blood orange juice

3/4 cup sugar

INSTRUCTIONS: To make candied Buddha's Hand: Starting at the large end of the citron, cut crosswise into scalloped slices about 3/16-inch thick. You should get about a dozen slices before you reach the fingers. You can slice the fingers into thin strips and candy them later by the same method.

Put citron slices in a large saucepan with 3 inches of cold water. Bring to a boil, then reduce heat to low and cook gently until slices are translucent, about 10 to 20 minutes. Carefully lift them out with tongs and arrange on a rack. Discard cooking water.

Put 3 cups sugar in a large saucepan with 3 cups water and bring to a boil, stirring to dissolve sugar. Add citron slices and adjust heat so they cook without boiling. Cook 30 minutes, then set aside to cool in the syrup. When cool, refrigerate slices in the syrup.

To make the sorbet: In a small saucepan, combine 3/4 cup blood orange juice with sugar. Warm gently, stirring, just until sugar dissolves. Stir the sweetened juice into remaining juice and chill thoroughly, then freeze in an ice cream freezer according to manufacturer's directions.

To serve, lift citron slices out of the syrup carefully and wipe off poaching syrup. Place them inside martini glasses or on individual plates and top with blood orange sorbet.

ECHO'S CHICKEN BREASTS WITH CITRON

This dish is adapted from a recipe from Tim Woods, chef of Echo restaurant in Fresno.

INGREDIENTS:

4 boneless chicken breasts

Salt and ground black pepper

1 cup chicken stock

1 shallot, thinly sliced

1/4 cup thinly sliced citron

1 tablespoon olive oil

1 tablespoon grated citron zest

1 tablespoon minced parsley

1 tablespoon unsalted butter

INSTRUCTIONS: Preheat the oven to 400 degrees. Season chicken with salt and pepper. In a small saucepan, combine the stock, shallot and sliced citron. Simmer over medium heat until reduced to 1/2 cup. Strain and reserve the citron-flavored broth.

Heat a large ovenproof skillet over high heat. Add the oil and swirl to coat. Add the chicken, skin side down, and reduce the heat to medium-high. Saute until nicely browned, about 2 minutes, then turn and cook 2 minutes on the second side. Transfer the skillet to the oven and cook until the chicken is firm to the touch, about 6 to 7 minutes more. Transfer the breasts to a platter.

Pour off any fat from the skillet and return the skillet to medium heat. Add the citron broth and simmer, scraping up any browned bits, until liquid is reduced to about 1/4 cup. Add citron zest and parsley and remove from heat. Add butter and swirl the skillet until the butter melts and thickens the sauce.

INSALATA'S WALNUTS WITH KUMQUATS & PICHOLINE OLIVES

This simple appetizer from chef Heidi Krahling should be served with other Middle Eastern mezze such as hummus or taramosalata. If you can't find pitted picholines, smash unpitted ones with the flat side of a knife to break the skin and remove the pit, but do not chop further.

INGREDIENTS:

1 cup toasted walnuts, in large pieces

1/2 cup pitted picholine olives

5 kumquats, seeded, trimmed, very thinly sliced

3 tablespoons coarsely chopped Italian parsley

3 to 4 tablespoons extra virgin olive oil

Salt and freshly ground pepper, to taste

INSTRUCTIONS: Combine all the ingredients in a bowl and serve at room temperature.

SEVILLE ORANGE MARMALADE

This recipe is adapted from ""Room for Dessert" by David Lebovitz (HarperCollins, 1999). The recipe may be doubled.

INGREDIENTS:

3 Seville oranges

1/2 navel orange

5 cups water

4 1/2 cups sugar

1 tablespoon Cognac or Scotch, optional

INSTRUCTIONS: Wash the oranges well and cut away the stem. Halve and juice the fruit, reserving the juice. Cut the juiced halves in half again. Pull out the tough interior membrane (a serrated grapefruit spoon works well here). Salvage as many of the seeds as you can and tie them together in a cheesecloth bag. Slice the quartered orange rinds as thin as possible. (You may want to cut the rinds into smaller pieces before slicing so the slices aren't too long. )

The next day, stir the sugar into the mixture and set the pot over high heat. Bring the mixture to a boil, then reduce the heat to maintain a gentle simmer. Stir occasionally during cooking to make sure marmalade is not burning on the bottom. If white foam rises to the top, skim it off.

Continue cooking until the marmalade reaches 220 degrees, about 1 hour. Turn off the heat and put a small amount on a plate that has been chilled in the freezer. Return the plate to the freezer, and after a few minutes, check it by nudging it with your finger. If it wrinkles, it has jelled. If not, continue cooking the marmalade and retesting for jell. When it's ready, add the optional Cognac or Scotch.

Remove the cheesecloth bag and ladle the marmalade into hot sterilized jars and top with clean lids and rings. The jars should seal as they cool. If they do not seal, keep refrigerated. Sealed jars may be stored in the pantry.